Wayne,

I agree that the BBS shows many species of birds increasing. I don't
think the same is true for most native vertebrates. I doubt if you
would find the same thing if we had similarly rigorous surveys of
herps, mammals, freshwater fishes, or marine fishes, not to mention
native mollusks, butterflies, moths, etc. I know of only a few
species of North American dragonflies that are clearly increasing,
and - just like the birds - they are species that do very well in
modified habitats. Many of the species of plants and animals
obviously increasing in North America are invasive aliens. Plenty of
evidence for that.

Declines in insect abundance and diversity are extremely hard to
prove, but I have no doubt they have happened and are happening. I
would love to see evidence to prove me wrong!

We are putting a lot of effort into helping birds by creating
wildlife refuges and preserves, and many species of birds and some
other wildlife species are surely benefitting from that, at least on
a local scale. I would maintain that with continued human population
growth, we will eventually have nothing but these preserves, islands
of wildlife habitat in a matrix of human habitat (for a long time it
was the other way around). You may call such statements "alarmist,"
but I guess I call it facing the facts. Short of massive human
population declines as a consequence of epidemics, I can't think of
any other plausible scenario. I assume I don't need to cite the
evidence for human population increase or habitat destruction.

Most of the Breeding Bird Surveys are out in the countryside, and
while there is steady habitat loss around the cities, which of course
is what we've been writing about on tweeters, the countryside is also
changing, but in different ways. For example, in many areas there is
now more woodland as small farms are abandoned because small-scale
farming is being replaced by agrobusiness. Thus woodland birds are
increasing locally. Agrobusiness tends to be developed in areas that
are already open habitats, and without looking at the data, I doubt
if the BBS shows increases in grassland birds. I wish I had time to
analyze the BBSs that you cite to see what types of birds are
decreasing and increasing and try to make some predictions about the
likely continuation of both trends. For example, I can envision
Violet-green Swallows increasing as more and more people move out
into the country and put up bird boxes in their yards, but fast-
forward 50 or 100 years to when that particular spot has been
incorporated into a city, and just as in Seattle, I predict the birds
will decline.

I should add that I don't have to write only as a scientist. I'm a
concerned human being who has been around long enough to see these
changes for myself, and by no means do my statements reflect only
what I've seen in my yard. Drive out into the Columbia Basin any time
if you need to be convinced of dramatic changes and diminished
wildlife! If my comments implied I was thinking only of North
American birds, I assure you that my thoughts extend much more
widely. I've traveled all over the world, and I've seen for myself
many of the changes that I've also read about happening elsewhere, as
I'm sure you have as well. I'll stick to the statement I made
earlier: "Basically, we're making the world worse for birds and other
wildlife . . ." And, from your second paragraph, I would say we
probably agree.

Dennis
-----
Dennis Paulson
1724 NE 98 St.
Seattle, WA 98115
206-528-1382
dennispaulson at comcast.net

On Jul 22, 2006, at 10:18 AM, Wayne C. Weber wrote:

> Dennis,
>
> I have enormous respect for your knowledge and your accomplishments
> as a scientist. However, I find some of your comments about declines
> of birds and insects to be disturbingly unscientific and poorly-
> documented.
>
> I do not disagree with you that the net effect of human population
> growth
> and development on biodiversity is negative. If even a few species of
> birds or insects disappear from a large area, that is a bad thing
> and a
> cause for great concern. This is certainly happening in North America
> and elsewhere.
>
> However, your statement that "we're making the world worse for
> birds and
> other wildlife, except for a select bunch of species that are
> adapting very well to the conditions we create ..." strikes me as
> inaccurate and alarmist. For birds at least, there is a large
> number of
> species, not a small number of species, which have increased in
> abundance as a result of human-caused habitat changes. I can provide
> documentation for this statement.
>
> For birds in North America, one of the best indicators of
> population change
> is the Breeding Bird Survey, sponsored by the US Fish & Wildlife
> Service-- a project which includes numerous TWEETERS subscribers
> as participants. I looked at the latest summary of bird population
> changes
> in Washington on the BBS website, for the period 1968 to 2004,
> based on
> results from more than 90 BBS routes. These results indicate that,
> for 199 species included in the table, only 78 have shown population
> declines over this long time period, while 121 have shown increases.
>
> It should be emphasized that most of these "increases" and "decreases"
> are small, and are not statistically significant. However, even if one
> restricts
> comments to species that show statistically significant changes, in
> general the BBS shows as many species with increases as with
> decreases.
>
> Let's look at the 3 species you specifically mentioned-- Violet-green
> Swallow, Barn Swallow, and Vaux's Swift. It may be that all 3 of these
> have significantly decreased in your neighborhood, or even in greater
> Seattle overall. However, this does NOT mean that they have all
> decreased statewide. You may be unreasonably extrapolating from
> your own local area to a much larger area.
>
> Barn Swallows have definitely shown a major long-term decline in
> Washington, which is evident also in BC and probably in other nearby
> areas. For the period from 1968 to 2004, Barn Swallow populations
> have declined at a rate of 3.2 percent PER YEAR, which is
> statistically significant at the 95% level-- a shocking rate of
> decrease. (However, there are still an average of 17 Barn Swallows
> seen per BBS route-- they aren't extinct yet.)
>
> On the other hand, Violet-green Swallows have INCREASED statewide
> at an average rate of 2.0% per year. At the 95% rate, this increase is
> not statistically significant, but it is significant at the 90% level.
>
> Vaux's Swifts show a small decrease-- 0.7% per year-- which is not
> statistically significant, and may not be real.
>
> So of the 3 bird species about which you expressed concern, one
> is definitely decreasing, one is increasing, and the third shows
> no significant population change at the statewide level.
>
> I frequently hear from various long-time birders that Species X or
> Species Y, or birds in general, have dramatically decreased over
> the last 30, 40, or 50 years. However, I attribute many (not all)
> such comments to over-generalization based on a very small local
> area, or even to a faulty memory about "the old days". The role
> of declining hearing, at least, in older birders should also be
> taken into account. This almost certainly does not apply to your
> swallows and swifts, Dennis, but many supposed "declines" of birds
> described by older observers are a result of declines in their
> hearing,
> NOT declines of the actual birds.
>
> So Dennis, if you expect to convince us of the reality of some of
> these
> supposed declines, please provide better evidence in future!
>
>
> Wayne C. Weber, Ph.D.
> Delta, BC
> contopus at telus.net
>
>
>
>
>
> ----- Original Message -----
> From: "Dennis Paulson" <dennispaulson at comcast.net>
> To: "Tweeters" <tweeters at u.washington.edu>
> Sent: Friday, July 21, 2006 7:53 AM
> Subject: Re: [Tweeters] insects and swallows
>
>
> Like Diann MacRae, we have lost the Violet-green and Barn Swallows
> and Vaux's Swifts that we would see just about daily over our house
> when we first moved in here 15 years ago. I occasionally see all
> three species, but very infrequently now.
>
> It's worth considering that these species have declined (also)
> because of loss of nest sites or nest material, subtle but continuous
> changes that would be very difficult to monitor (just like insect
> abundance). Violet-greens need crevices - maybe there are fewer all
> the time. Houses are being replaced by condos, which perhaps are very
> well sealed against the outside world, as are the houses being built
> currently. Barn Swallows need mud, as well as ledges, and I've often
> thought that mud is surely declining in urban areas, as our
> surroundings are tidied up. I think both of these species have
> declined all over Seattle since I've lived here. Vaux's Swifts need
> either snags or chimneys, and the former may well be decreasing,
> especially of the size needed by the swifts, while fewer and fewer
> chimneys may present nesting opportunities because of the way they
> are constructed.
>
> It's fascinating to read the accounts of insect abundance by
> different contributors, reporting disappearances, declines,
> abundances, "too many." I would say that insects have not changed in
> abundance in my yard in 15 years, but there weren't many to begin
> with. Because of my long time spent in the East, as well as recent
> visits in summer, I will reiterate that "bugs" back there are 10x as
> abundant (and at least several times as diverse) in forested habitats
> as they are in forested habitats in the western Washington lowlands.
> In any little sunny clearing back there, you could catch or
> photograph insects for several hours and not begin to exhaust the
> species present, whereas around here I see the same small number of
> species again and again. I see in my wooded "natural" yard pretty
> much the same list of 30 or so insects and spiders that Christine
> Southwick reported in her Shoreline yard (and thank goodness there
> are at least that many), but I consider it a woefully inadequate
> representation of biodiversity, when you realize there are 91,000
> described species of insects in the US. I'm sorry I haven't had the
> time or foresight to make a continuing collection of all the insect
> species in my yard, and that would be a great project for an urban
> entomologist anywhere.
>
> But that's a digression; the same things are happening continentwide
> and worldwide. Basically, we're making the world worse for birds and
> other wildlife, except for a select bunch of species that are
> adapting very well to the conditions we create as we destroy natural
> habitats and replace them with human habitats. If we understood all
> the variables, what we see happening is probably quite to be
> expected. It should be relatively easy right now to predict which
> North American birds will still be common in 50 or 100 years!
> -----
> Dennis Paulson
> 1724 NE 98 St.
> Seattle, WA 98115
> 206-528-1382
> dennispaulson at comcast.net
>
>
>
>
>

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